Odour prevention in connection with the use of absorbent products, such as incontinence and/or feminine products is an important comfort factor for consumers. Bodily fluids, such as blood and urine, are collected and stored in absorbent products and odours may easily arise. It is important for the wearer that these odours do not spread into the environment and the wearer needs to feel safe when using absorbent products both in respect of leakage and odour prevention or control.
In the field of absorbent products, several different solutions are used to prevent odours. For example, odours can be masked by the use of perfumes or deodorizing compounds. Odours may also be adsorbed or absorbed to particles having a large surface area, such as activated carbon, zeolite and starch-based particulate materials. Acidic and/or alkaline odours may be neutralized by the use of substances like baking soda and/or citric acid. For bacteria inhibition, substances having low pH or metal salts can be used. Accordingly, different odour control agents may be used to prevent odours in different manners.
Odour control agents in particulate form, such as the above-mentioned activated carbon, zeolite and starch-based materials, have been proved to have excellent odour-adsorbing characteristics due to the large surface area of the particles. However, there are some drawbacks related to the use of such particulate odour control agents, which may be in a powder form: for example, such powders are very difficult to handle in dry processes due to dusting problems. Powders may contaminate both process equipment and products. The powder may be spread in the working environment and in the worst case contaminate the working environment and/or cause dust explosions.
Further, problems with appearance of white absorbent products may arise if the powder, for example activated carbon powder, dusts during the manufacture of the products. The activated carbon may be spread in the products also outside the desired positions and therefore deteriorate the appearance of the products. It is desirable to keep the products clean outside the areas where the odour control agent is aimed to be positioned.
Particulate odour control agent powders may also be difficult to disperse in an even manner in the absorbent products. For example, humidity of the atmosphere may cause the particulate material to build lumps, and this may cause an uneven distribution in the production process and consequently in final products. Further, since particulate odour control agents adsorb odorous substances from the ambient air, there is a risk that the adsorption capacity of the particles decreases under storage.
In the prior art, there have been attempts to decrease dusting problems of powders as for example disclosed by EP0392528, in which a particulate odour control agent is bound to a fibrous base web, such as non-woven or paper web. The porous base web is dipped in a saturant slurry containing the odour-absorbing particulate and a binding agent, together with a surfactant. The excess slurry is then squeezed from the web and the web is dried. According to EP0392528, it is essential that the particulate material is effectively bound to the base web. Accordingly, a base web is needed to carry the odour-absorbing particles and the web as a whole is used in a final product. Therefore, possibility to use this web material is limited to products where the base web is needed as a part of the end product. This may complicate the production process and result to an expensive final product. Also, since the odour-absorbing particulate material is bound to the fibre web, the whole surface area of the odour-absorbing material is not used for absorption of odours. Further, the odour-absorbing material is exposed to the surrounding environment, whereby the odour-absorbing properties of the particulate material may be impaired during storage.
Thus, there is still a need to improve handleability of particulate odour control agents while good odour adsorbing/absorbing properties are maintained or improved, especially after storage.